Question

f(x)=3-2x Rezolvati inecuatia x+2-f(2x) mai mic sau egal cu 3

Answer 1

f(x) = 3 - 2x

x  + 2 - f(2x) ≤ 3

f(2x) = 3 - 2 · 2x = 3 - 4x

⇒ x + 2 - ( 3 - 4x ) ≤ 3

x + 2 - 3 + 4x ≤ 3

5x ≤ 3 + 3 - 2

5x ≤ 4

x ≤ 4 / 5 ⇒ x ∈ ( -∞ , 4/5 ]